Sludge around the sending unit maybe. The 4.7 is notorious for it, but it's not entirely uncommon on the Hemi. Pick up a can of Seafoam and use it with conventional oil and change out to a synthetic after 1000-1500 miles.
The properties of synthetic oils work to keep Seafoam and other like products off the metal surfaces, where they need to do their job. So by using them with a conventional oil lets them work best...

 

Thanks for that. I was definately going to switch to synth the first time I change my oil.

Seafoam? Never heard of it. I'll look for it at Wal Mart or Autozone.

 

When I got my truck, I was only getting 13.5mpg highway....course it didn't help it had 285R/50/20 aggressive tires and a 3.92 ratio. Actually going to the stock size tires and the Air Stream made the biggest difference in mileage. Now I get 16.5 city and 21.5 highway @ 70mph. Course I've put a lot of mods on my truck, with a MotoBlue underdrive pulley, high flow cat, and mid-tube headers with y-pipe on the list, after that hopefully 23mpg highway. No, I won't recoup the cost for a while but it's nice to have a big truck that gets sedan mileage. Besides, it's pretty peppy for a truck!

 

16.5 city? Are you sure about that?

Since I originally made this post the pcm was reset at the dealer due to a repair, I added a cai and 10lbs of air to the tires and now get 10.4 mpg hand calc and 13 highway. The 13 highway is at 85mph and with cruise control so I might be able to improve that.

With all that said, thats about the same mileage I'd get out of a V10 F350...so there may be a change soon.

 

Driving a 4.7 quad cab. Getting 12.1 city by both my math and the trip calc. Which I consider decent since to get to work is only a 1 mile drive that has 2 stop signs and 2 stop lights. So it could be doing better. Only thing not stock is the air intake.

Need to change the plugs and will switch to synthetic on the next oil change. Will get a chance to test the highway on a couple 300 mile highway stretches coming up in a few weeks.

I'm sure it will go down when I get my new exhaust installed this weekend too... I know I will be stomping it...

 

sounds completely normal to me depending entirely on how I drive i can get from 10.8-12.7 most of the time the foot likes to be heavy so i sit aroun 12.1 which is good if I drive the speed limit on the highway you can get about 16+ the biggest gas saver is to not lead foot it lol

 

subscribing! I am looking at a similar ride

 

Reviving an old thread I guess? I've actually recently sold the truck for a F350 4x4 cc lb srw with the 6.0 powerstroke....and actually the mpg is about the same after I did a turbo back exhaust, tuner, and cai... but better mpg towing (this is also with a 1,000lb dump insert on the truck). When all was said and done, I almost never drove the Ram in the last 2 years without a 8,000lb trailer behind it (24' enclosed car hauler loaded to max capacity and then some) and still got an average of 10.5mpg (mostly city with some rural mixed in). Even in the winter with a just the plow on it I still got about 14.5mpg (with winter gas and plowing included). Mods I had on it were irridium plugs, Taylor plug wires, (had e fans but took them off for reliability, made about .5mpg difference), VariRam intake, DiabloSport Predator tuner running 87 octane tune, airiad throttle body spacer, Flotech ceramic coated mid length headers, y-pipe with full 3" output (had to cut the end of the pipe and weld on the cat), Monsterflow 3" cat, dynomax 3" muffler, Fitch fuel catalyst drop-ins in the tank (not the inline), air tabs, LRR stock size tires, Amsoil synthetics everywhere (ran 0w20 in the engine and changed every 15k miles with towing), helper springs in the back, and flush truck topper. When towing I could get a little over 200 miles per tank (mostly city), the few times I didn't have the trailer or plow on it I could get just over 400 miles per tank (mostly highway).

 

Just saw an email for the reply to this thread I started in 2009! Forgot I even did this.

I still have the truck. For whatever reason the has mileage has improved to around 11 in town stop and go driving and will do about 12-12.5 with some highway thrown in.

I now have 84000 miles on it. There have been some repairs like ball joints at 40k, a water pump at about 50k and a leaky front axle seal that I didn't think I should have to do at such low mileage. I had to do another water pump and fix a cracked transmission filter as well.

Both my wife's Cherokee Laredo and my truck started using oil after 60k so you really need to keep an eye on that.

If I were in the half ton market again I would definitely choose something else. I think you'll get better mileage and reliability with just about anything. I'd be looking at a Nissan titan pro-4x or a Toyota tundra.